An ongoing trend in the computer and video games industry is to make the gameplay experience feel more cinematic. Much time and energy has been spent on improving realtime visual rendering systems, physics simulations, artificial intelligence modeling, dynamic audio mixing, etc. and great strides have been made in these areas.
With the exception of cutscenes, which are short films within which the player of the game in question has little to no control over, music and audio is played back in response to what the player does. In a basic implementation, the game developer may loop a background music track (BGM) for the duration of a level. In more complicated implementations, the game developer may transition the background music track to a more sinister-feeling one when the player encounters a tough enemy. In this way, the game developer subtly affects the experience, just as the composer of a movie soundtrack can play a sad note during a break up scene in a movie.
Film soundtrack composers generally write their music after filming has completed and a rough cut version of the film exists. In this way, they can plan the progression of the accompanying music to match the events and emotions of the action and actors on screen.
Unlike the film soundtrack composer, however, the game musician typically cannot know how the action will play out when the game is played by a player as the action and timing thereof is partially, if not completely, determined by the players themselves. In this way, the player acts as a kind of director. The music, however, must be completed before the game is deemed finished and allowed to reach the hands of the player. Due to this restriction, game musicians write their music in such a way as to evoke a specific emotion from the player: generally sad music for a sad part of the game, exciting music for action or battle scenes, and eerie music for scary scenes. They target an emotion or feeling with their composition, rather than specific events. This is in contrast to movie composers who write their music to align with the events on screen, accentuating specific moments or actions.
Certain prior art systems use pre-scripted sequences of events that specifically time with the background music. A horror game may have a string instrument playing an eerie note for an extended period of time, building in volume as the player approaches a door. When the player presses the button to open the door, the animation is slightly delayed such that the timing will work with the audio mix. This method puts strict limitations on how audio may be prepared and requires heavy custom work to get everything to synchronize properly. It also cannot be used in sequences involving fast-paced action as the music would have to change too quickly to be feasible for a general solution.
Another problem posed by interactive software such as computer and video games, is frequently inconsistent framerate. Framerate fluctuations and inconsistencies from computer to computer can cause serious problems with systems designed for visualizations (as appear in some prior art). If framerate drops or fluctuates enough, some events may be skipped entirely, or otherwise all triggered at once. For interactive applications, this will result in undesirable effects like multiple events appearing to happen concurrently, rather than separated out as per the source beats in the music to which the experience is being synchronized.